Question: Who was the person that was a student of Gustav Mahler?
Paraphrase: Who was the individual that was a understudy of Gustav Mahler?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P1066 wd:Q7304 . ?sbj wdt:P31 wd:Q5 } 
Answer: Anna von Mildenburg, Lula Mysz-Gmeiner